This invention relates to improvements in a side support assembly having side supports provided at the left and right sides of a backrest in order to maintain the posture of an individual occupying a seat in an automotive vehicle, especially a sports car. More particularly, the invention relates to a side support assembly of the type described in which the left and right side supports are swung back and forth to symmetrically adjust their position relative to a seated individual and held at the position to which they have been set.
When the direction in which an automotive vehicle is traveling is changed, an inertial force acts upon the individuals riding in the vehicle. Though the individual may attempt to follow the change in direction by trying to resist the influence of inertia, the inertial forces can be great enough to throw the individual toward the left or right side of the vehicle. If the individual is the driver of the vehicle, such a forcible change in posture can have a deleterious effect upon the ability to steer the vehicle. For this reason, there is a growing tendency for sports cars to come equipped with a side support assembly installed in the driver's seat.
A side support assembly of this type is disclosed in the specification of Japanese Utility Model Kokai Publication No. 57-204942. The disclosed side support assembly includes left and right frames each constituting the structural elements of a side support. Each frame has a freely rotatable operating shaft provided longitudinally of a backrest frame, the shafts being located at the left and right sides of the backrest frame. A connecting rod for rotating the operating shafts back and forth is provided transversely of the backrest and is coupled to the operating shafts at both ends thereof by links in such a manner that the left and right side supports may be swung back and forth horizontally and symmetrically. Means for swinging the frames of the left and right side supports in this manner is directly provided on one of these frames. The swinging means comprises a nut pivotally supported on the frame so as to be capable of swinging back and forth, and a screw shaft threadedly engaged with the nut and supported for free rotation at a prescribed position.
The disclosed side support assembly is not specially provided with a locking mechanism. However, since the operating mechanism of the swinging means is such that turning the screw shaft advances the nut to swing the frames, a force transmitted to the nut from the frames does result in rotation of the screw shaft. Thus, the swinging means doubles as a locking mechanism.